DST once referred to as "War Time"
https://www.defense.gov/explore/story/Article/1779177/daylight-saving-time-once-known-as-war-time/
It wasn’t until World War II began that the issue came up again. In February 1942, Congress implemented a law instating a national daylight saving time to help conserve fuel and "promote national security and defense," which is why it was nicknamed "war time." The time zones were even known as that: Eastern War Time, Pacific War Time, etc.